01 - Bring a large pot of salted water to a rolling boil. Add fusilli or rotini and cook according to package directions until al dente. Drain thoroughly and rinse under cold running water to halt cooking. Set aside to cool completely.
02 - Place corn ears on a preheated hot grill or grill pan. Cook for 8 to 10 minutes, rotating every couple of minutes, until kernels are lightly charred and blistered on all sides. Let cool until comfortable to handle, then stand each ear upright and slice kernels from the cob. If using frozen corn, sauté in a dry skillet over high heat until edges take on a golden char.
03 - In a large mixing bowl, combine mayonnaise, sour cream, lime zest, lime juice, chili powder, smoked paprika, cayenne pepper if desired, sea salt, and ground black pepper. Whisk vigorously until the dressing is smooth and fully blended.
04 - Add the cooled pasta, grilled corn kernels, diced red bell pepper, finely diced red onion, sliced green onions, and chopped cilantro to the dressing. Toss everything together until all ingredients are evenly coated.
05 - Gently fold crumbled cotija cheese into the salad. If including jalapeño and avocado, add them at this stage and fold with care to keep the avocado pieces intact.
06 - Cover and refrigerate the salad for at least 30 minutes so the flavors meld together. Taste before serving and adjust salt, pepper, or lime juice as needed.